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The box plot below shows the total amount of time, in minutes, the students of a class surf the Internet every day: Part A: List two pieces of information that are provided by the graph and one piece of information that is not provided by the graph. (4 points) Part B: Calculate the interquartile range of the data, and explain in a sentence or two what it represents. (4 points) Part C: Explain what affect, if any, there will be if an outlier is present. (2 points)
I hate box and whisker... there are two ways to calculate some of the items on them, which result in slightly different numbers. Anyhow, do you know what the number on the box itself mean?
no not sure
OK, when you do a box and whisker, you find the quartiles, or quarters, of the data. So basically uoi break the data into 4 parts. The line between the first quarter and second quarter is the first quartile and the line that is the edge of the lower end of the box. Betweent he 3rd and 4th quarter is the 3rd quartile, which is the far edge of the box. So the box encloses half the data.
THe line inside the box is the median of the data. The whisters go out to the high and low lines of the data.
If you look at your plot, you can see your highest ws 95 and lowest was 20, but the box is closer to the 20 side so more numbers were low rahter than high.
ok i see
Now, some of that is what you need to answer what is on the graph... but, what is NOT there is one of the questions. So, can you tell me something you can't get from the graph?
Well, here is a clue. It says it is for a class... but, what does it not say about that class of students?
the students that surf the Internet every day
No, it says that they do... but there are a couple things about that class that are simply not there. Hmmm.... If I said a class is large or a class is small, what number am I talking about?
LOL. I think you misunderstood me. Let me try again. OK... Umm, if I said, "He is in a large class." or "She is in a small class." what number am I talking about. Just in general. It also relates to your problem, but what would I normally be talking about?
Your talking about the number of students in each class?
Exactly. So, how many students are in the class on the plot? (This is a trick question...)
erm i wanna say 50 but i think thats minutes
That was the trick part. See, it can't be answered because it is not there. The plot does not say if this is a small, private school's honor's course with 12 students or an online school with 500 students per class. It does not say of they are predominantly black, female, or even English speaking. Basically, anything about the student composition is not on the graph. That is one of the limits to this sort of graph.
Yah... it is harder to see what is not there than what is, but that is what they mean. You have a graph that generalizes the data. This could be a small group of dedicated studies that have no time for the internet, or it could be a huge group of inner city kids that don't even have computers at home so they don't get to surf. No way to tell which. As for the last two, I would look at this page: http://www.purplemath.com/modules/boxwhisk3.htm Right near the top it talks about the interquartile range and how it relates to outliers.
I hope that helps you answer those in a way that will get you full points. Also, I hope you remember it. Box-and-whisker plots are useful tools and if you ever look at stocks or any sort of scientific data, you will need them. So getting an understanding now will rep you for seeing them in the future.
prep you... that is.
when they say Calculate the interquartile range of the data, and explain in a sentence or two what it represents. how would i go about that?
It says right at the top of that page I linked: Q3-Q1.
Other way round. 60 - 40 = 20.
it represents the range of minutes right?
Well, the width of the normal. It is the width of the box, which is the width of half the respondants. The first two paragraps on that page I linked do a really good job of describing it and outliers.
If an outlier is present it can skew the results. is that good?
That is not bad. You could add, "by making one or both whiskers longer than they should be."
Well, an outlier, just one, would only do one whisker...
Outliers, plural, could do one or both.
Perfect! Thank you so much for having patience with me and helping me even if i was struggling (:
Well, I like to more nudge people in the right direction. Then they do more of the work and can remember it better. Oh, and how I remember "outlier" is "oddball." They have the same initial and basica meaning. There was a 7'7" tall woman, which is an outlier for female height and odd to see. Odd as it was, she lived and was one of us. So outliers exist, they are just not normal. Now, other outliers are the odd mistake. Like the person that multiplies when they meant to add. 10+10=20, but 10*10=100! On a list of results from a lab, that 100 might be that sort of mistake, which is odd, so you discount it.